package ogg

import (
	"bytes"
	"encoding/binary"
	"errors"
	"fmt"

	"gitee.com/general252/gomedia/go-codec"
)

var (
	CapturePattern [4]byte = [4]byte{'O', 'g', 'g', 'S'}
)

// Ogg Page Head
// 0                   1                   2                   3
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |      'O'      |       'g'     |        'g'    |     'S'       |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |    version    |  header type  |                               |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               :
// |                         Granule Position                      |
// :							   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |                 			   |   Bitstream Serial Number     |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |    Bitstream Serial Number    |      Page Sequence No         |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |       Page Sequence No        |         Checksum              |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |           Checksum            | Page Segments |               |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               :
// |                       Segment Table                           |
// |                            ....              		           |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

const (
	PAGE_HEAD_LENGTH = 282
)

var crc_table [256]uint32 = [256]uint32{
	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
	0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
	0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
	0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
	0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
	0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
	0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
	0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
	0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
	0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
	0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
	0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
	0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
	0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
	0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
	0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
	0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
	0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
	0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
	0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
	0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
	0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4,
}

func makeChecksum(crc uint32, buffer []byte) uint32 {
	var checksum uint32
	for index := range buffer {
		checksum = (checksum << 8) ^ crc_table[byte(checksum>>24)^buffer[index]]
	}
	return checksum
}

type oggPage struct {
	version          byte
	isContinuePacket bool
	isFirstPage      bool
	eos              bool
	granulePos       uint64
	streamId         uint32
	pageSeq          uint32
	checkSum         uint32
	segmentsCount    uint8
	seqmentTable     [255]byte
	payloadLen       uint16
	packets          [][]byte
	cache            []byte
}

func readPage(data []byte) (*oggPage, error) {

	if !bytes.Equal(data[:4], CapturePattern[:]) {
		return nil, errors.New("capture pattern not found")
	}
	var page = &oggPage{}
	data = data[4:]
	page.version = data[0]

	if data[1]&0x01 > 0 {
		page.isContinuePacket = true
	} else {
		page.isContinuePacket = false
	}
	if data[1]&0x02 > 0 {
		page.isFirstPage = true
	} else {
		page.isFirstPage = false
	}
	if data[1]&0x04 > 0 {
		page.eos = true
	} else {
		page.eos = false
	}
	page.granulePos = binary.LittleEndian.Uint64(data[2:])
	page.streamId = binary.LittleEndian.Uint32(data[10:])
	page.pageSeq = binary.LittleEndian.Uint32(data[14:])
	page.checkSum = binary.LittleEndian.Uint32(data[18:])
	page.segmentsCount = data[22]
	copy(page.seqmentTable[:], data[23:23+int(page.segmentsCount)])
	page.payloadLen = 0
	for i := 0; i < int(page.segmentsCount); i++ {
		page.payloadLen += uint16(page.seqmentTable[i])
	}
	return page, nil
}

func PrintPage(page *oggPage) {
	fmt.Printf("version:%d\n", page.version)
	fmt.Printf("Stream id:%d\n", page.streamId)
	fmt.Printf("granule position:%d\n", page.granulePos)
	fmt.Printf("continue with last page:%v\n", page.isContinuePacket)
	fmt.Printf("first page:%v\n", page.isFirstPage)
	fmt.Printf("last page:%v\n", page.eos)
	fmt.Printf("page sequence:%d\n", page.pageSeq)
	fmt.Printf("segment count:%d\n", page.segmentsCount)
	fmt.Printf("segment table:%v\n", page.seqmentTable[0:page.segmentsCount])
}

type oggStream struct {
	currentPage *oggPage
	streamId    uint32
	cid         codec.CodecID
	parser      oggParser
	lost        int
	cache       []byte
}
